The present invention relates to a integrated circuit packaging and, more particularly, to packaging a lead frame based semiconductor die package.
A semiconductor die is a small integrated circuit formed on a semiconductor wafer, such as a silicon wafer. Such a die is typically cut from the wafer and packaged using a lead frame. The lead frame is a metal frame, usually of copper or nickel alloy, that supports the die and provides external electrical connections for the packaged die. The lead frame usually includes a flag (die pad), and associated lead fingers (leads). The semiconductor die is attached to the flag and bond or contact pads on the die are electrically connected to the lead fingers of the lead frame with bond wires. The die and bond wires are covered with an encapsulant to form a semiconductor die package. The lead fingers either project outwardly from the encapsulation or are at least flush with the encapsulation so they can be used as terminals, allowing the semiconductor die package to be electrically connected directly to other devices or to a printed circuit board (PCB).
Semiconductor die packages are being manufactured with an increased functionality to package pin count (external terminal or I/O count). This is partly because of improved silicon die fabrication techniques that allow die size reductions. However, the number of lead fingers is limited by the size of the package and the pitch of the lead fingers. In this regard, a reduced lead finger pitch generally increases the likelihood of short circuit faults particularly when the package is mounted to a circuit board.
One solution that may overcome or alleviate circuit board shorts due to reduced lead finger pitch is to space adjacent lead fingers in different planes. The mounting feet at the ends of adjacent lead fingers are spaced at different distances from the package housing and thus this increases the spacing of the circuit board pads to which the mounting feet are soldered. Although useful, the spacing of adjacent lead fingers in different planes can increase the manufacturing process complexity and requires accurate jig alignment and precision lead bending.